In manufacturing a converted product in the form of a tissue or a towel product or the like, some of the desirable characteristics of the converted product are bulk, which is believed to be desirable for visual aesthetics and marketability considerations, and softness (or at least the consumer's perception of softness), which is believed to be important for market acceptance. Another desirable characteristic is that the product should retain sufficient strength to allow high-speed converting. However, these desirable characteristics have conflicting requirements. For example, when embossing is used to make the product bulkier, the protuberances which it forms in the product tend to reduce the consumer's perception of softness. Greater softness in this context usually means less product strength, which tends to impede running the converting process at a speed commensurate with that of a typical papermaking machine. A converted product which is not very bulky may be perceived as sufficiently soft, but lower bulk product tends to be less desirable from aesthetic and marketing points of view, for example because the roll of tissue or towelling may seem smaller. While much effort has been devoted to finding acceptable compromises between these conflicting requirements, it is believed that a need still remains for achieving the desirable end results while reducing or eliminating the undesirable consequences, and this invention is directed to meeting this need.
It has been proposed in prior patents (such as U.S. Pat. Nos. 3,414,459, 3,547,723, 3,556,907, 3,775,231, 4,284,465, 4,307,141 and 4,325,768) to use various combinations and subcombinations of embossing and calendering, such as individually embossing a pair of plies and then joining them and calendering the resulting multi-ply web, or individually calendering and embossing plies and then joining them, or individually pre-embossing a pair of plies and then joining them and embossing the resulting web, or using a succession of out-of-register embossing steps, or pre-embossing and then joining, etc. However, it is believed that the particular sequence of the steps of pre-embossing, calendering, and then again embossing, and the particular way of carrying out these steps as taught in this specification produce substantially superior results but are not known in the prior art.